Stuffed zucchini is my favorite stuffed vegetable! But only if they are not too large (about the size of a tomato). I like to stuff a variety of vegetables in one pan — zucchini, tomatoes, bell peppers. Here is a good recipe:http://greekfood.about.com/od/vegetablerecipes/r/yemista_kal.htm.
You can also add a little ground beef.

It looks big enough that maybe you could adapt our pumpkin pilaf approach (recipe would be too precise). Gourd in big pot of water on low boil, things inside gourd, let it do that for about four hours, split open to serve. Let me know if you’d like more details.

I know what it is because I’m both a botanist and a CSA cook, but I refuse to tell you the name. Hate names. Who cares? You don’t need to tell the cashier what it is to buy it because you already paid for it.
And, I must say that you seem overly hooked on the Internet and visual sensory input. Be like the Naked Chef. Cut the thing open, note the resistance to your knife as it moves through, sniff, examine color of the flesh if you really want more visual info, perhaps probe a bit to see how moist and dense it is, figure out what to do with the seeds if any based on similar taste/smell/probe assay. Once you’ve re-integrated your senses a bit and found some inspiration …. cook, eat, enjoy.

Kabocha tends to be darker green, in all the varieties I know of.
(If Jamie Oliver is all about the “zen,”* then why does he sell instructions to us on how to cook? Hm?)
(*My experience with Zen temples is (1) lots of rules on how to behave and (2) getting hit on the head during meditation. I fail to see what’s zen about Zen. Although they may have ideas on what to do with squash. Haven’t asked.)

Sorry if I’m now irritating with an unwelcome genetics lesson, but for those who think it’s sort of neat … enjoy this linkhttp://www.liseed.org/acorndiv.html
I would suspect that, like many CSA farms, your farmers are growing this blend because they are experimenting with heirloom seed or seed saving or both. A sort of DIY off-the-grid mentality applied to CSA farming.
Ultimately all that matters: was it tasty?